2233 - Fabry Perot Etalon (1948)

ID:

2233

Maker's Name:

Hilger

Where made:

England

1948

Dimensions:

9.3 × 5.3 × 6.4 cm

Multiple reflections between carefully aligned partial reflectors result in narrow wavelength pass-bands when the mirror separation is an integer multiple of half-wavelengths. In this version of the Fabry Perot interferometer, called an 'etalon', the mirrors are held permanently in strict alignment by a fused silica spacer.

This unit was probably used in conjunction with a Hilger constant deviation spectrometer. Because the interference pass-bands are narrower than the linewidth of a prism spectrometer it can be used to make linewidth measurements with much higher resolution. It was purchased in 1948 for the sum of £35/10/-.